Large, industrial type horizontal axis wind turbines typically comprise a pitch regulation for controlling the orientation of their rotor blades with regard to the incoming airflow of the wind. In comparison to a stall regulated wind turbine, where the rotor blades are rigidly fixed to the hub of the wind turbine, in pitch regulated wind turbines the rotor blades are pivotable mounted to the hub. This has the advantage that the orientation of the rotor blades with regard to the incoming airflow can be chosen such that the amount of generated electricity by the wind turbine is optimized.
Typically, the rotor blades are mounted to the hub via a bearing comprising an inner bearing ring and an outer bearing ring. The bearing may be a roller bearing, for instance a tapered roller bearing.
As wind turbines become larger and larger and consequently the rotor blades become larger and larger the forces which are transferred from the rotor blade to the hub via the pitch bearing increase as well. Thus, a reinforcement of the pitch bearing is advantageous.
In order to reinforce the pitch bearing the European patent application EP 2 045 464 A2 discloses a pair of reinforcing plates. These reinforcing plates are arranged such with regard to the inner bearing ring that they build a sandwich-type closed structure.
However, deformation of the pitch bearing, in particular of the inner bearing ring and/or of the outer bearing ring, may still occur if extreme forces are applied to the pitch bearing.
Thus, it would be advantageous to provide a pitch bearing with a further improved stiffness.